Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• was paid on trifluoroacetates. Trifluoroacetate is readily available and one of the cheapest and most convenient sources of the trifluoromethylation for both industrial and medicinal purposes. In 2011, a practical and ligand-free Cu-catalyzed decarboxylative trifluoromethylation of aryl iodides was

• reported by the group of Li and Duan, with sodium trifluoroacetate as the trifluoromethyl source and using Ag2O as a promoter (Scheme 5) [17]. Subsequently, Beller and co-workers [18] finished a copper-catalyzed trifluoromethylation of aryl iodides with inexpensive methyl trifluoroacetate (MTFA) (Scheme 6

• aromatic trifluoromethylation step. The attractive prospect of trifluoroacetate as the trifluoromethyl source for the preparation of trifluoromethylarenes prompted the investigation of the mechanism of this reaction. A mechanistic study indicated that CuCF3 was formed by decarboxylation of the

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• persulfate by hypervalent iodine oxidants such as iodobenzene diacetate (PIDA, Scheme 28) [49], or iodobenzene bis(trifluoroacetate) (PIFA) [50]. Fu and co-workers proposed the reaction mechanism depicted in Scheme 28. PIDA reacted with CF3SO2Na under heating conditions to produce two radicals: CF3• along

• phenyliodine bis(trifluoroacetate) (PIFA) instead of tert-butyl hydroperoxide as the oxidant in hexafluoroisopropanol (HFIP) at room temperature [71]. In order to obtain good results for this transformation, it should be noted that the electron-donating nature of the aromatic substituents was a crucial point

• -workers reported the synthesis of trifluoromethylated coumarin 71 and flavone 72 with CF3SO2Na (2 equiv), the hypervalent iodine F5-PIFA (pentafluorophenyliodine bis(trifluoroacetate)) (2 equiv) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 0.6 equiv). The trifluoromethylated compounds were obtained

Base-promoted isomerization of CF₃-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

• Yoko Hamada,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 1507–1512, doi:10.3762/bjoc.13.149

• trifluoroacetate at −80 °C, a Horner–Wadsworth–Emmons reagent [17] activated by LiBr and Et3N [18][19][20] was introduced to this solution at room temperature, leading to the formation of (E)-6 after the NaBH4 reduction of the resultant products (see Supporting Information File 1 for the detailed procedure). As

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• sterically hindered pyrene 1-position, whereas the bulkier protonated acetyl trifluoroacetate (the postulated electrophile in the examined Friedel–Crafts acylation) attacks sterically the less hindered 4-position. Conclusion We found that triflic acid-promoted (thio)carbamoylation of 2 with aliphatic iso

A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE

• Tue Heesgaard Jepsen,
• Emil Glibstrup,
• François Crestey,
• Anders A. Jensen and
• Jesper Langgaard Kristensen

Beilstein J. Org. Chem. 2017, 13, 988–994, doi:10.3762/bjoc.13.98

• , MeOH, DCM) and was found to be unstable on silica. Thus, all attempts to purify the material through column chromatography or preparative TLC led to decomposition of the material. Also an attempted isolation of the amine as its hydrochloride or trifluoroacetate failed. Finally, the [6,6]-bicyclic

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• reactor at 25 °C for a residence time of 3 min to get the trifluoroacetate, which further reacts with triethylamine in a PFA coil (10 mL) at 100 °C for 5 min to give the final drug molecule. By using Vapourtec V-3 peristaltic pumps, the authors are able to achieve a constant fluid flow rate. Maintaining

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

• Youngeun Jung,
• Dileep Kumar Singh and
• Ikyon Kim

Beilstein J. Org. Chem. 2016, 12, 2689–2693, doi:10.3762/bjoc.12.266

• -dimethoxybenzaldehyde, and 3,5-dimethoxybenzyl alcohol under the influence of either I2/silver trifluoroacetate or N-iodosuccinimide afforded 1 [32][33][34], 2 [35], and 7 [36][37], respectively (Scheme 2). The hydroxy group of 7 was protected as an acetate, providing 3 in 96% yield. Sonogashira coupling of the

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II)-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

• Valerij A. Nikolaev,
• Jury J. Medvedev,
• Olesia S. Galkina,
• Ksenia V. Azarova and
• Christoph Schneider

Beilstein J. Org. Chem. 2016, 12, 1904–1910, doi:10.3762/bjoc.12.180

• catalyst and its ligands on the efficiency of the processes studied, non-fluorinated rhodium carboxylates (Rh2L4; L = OAc, Oct, Piv) and catalysts with trifluoroacetate or perfluorobutyrate ligands [Rh2L4; L = CF3CO2 (tfa), C3F7CO2 (pfb)] were used in this research. Results and Discussion In the beginning

Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

• Lena Huck,
• Juan F. González,
• Elena de la Cuesta and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2016, 12, 1772–1777, doi:10.3762/bjoc.12.166

• ether function existent in aziridine derivatives 2 because of the presence of the 2-methoxy substituent would furnish oxonium species 7 via a Neber reaction. Its O-demethylation by the trifluoroacetate anion would yield compound 8, whose amino group would finally be trifluoroacetylated by the methyl

• trifluoroacetate liberated in the previous step, to give 6. Alternatively, loss of a molecule of methanol from starting compound 2 would lead to intermediate 5 (see Scheme 3), whose reaction with trifluoroacetic acid would furnish 9. Neber-type chemistry would afford the oxonium species 10, which would finally be

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• trifluoroacetato ligands occurs [29], which is present in the solution in large excess. This potential intermediate of the catalytic cycle, the [(pym)^(NHC-R)PdII(CH3)(CF3COO)]-complex 13 (with R = 2,6-diisopropylphenyl), could be synthesized by the reaction of complex 11 with silver trifluoroacetate (Scheme 2

• methane is converted into methyl trifluoroacetate catalyzed by a Pd(II) complex. To examine if a methylated Pd(II) complex like 13 can be an intermediate of this reaction, potassium peroxodisulfate and sodium trifluoroacetate were added to a solution of 13 in DMSO-d6 or CDCl3. Analyzing the solution we

• could confirm the formation of methyl trifluoroacetate and a ‘methyl free’ Pd(II) complex. This complex showed similar NMR spectra like the bistrifluoroacetate complex 14 (Scheme 3), which was prepared by the reaction of the corresponding dichloro complex [34] with silver trifluoroacetate for comparison

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells

• Wei Li,
• Munechika Otsuka,
• Takehito Kato,
• Yang Wang,
• Takehiko Mori and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134

• potential of 20 kV. Dichloromethane solutions containing 1 g L−1 of a sample, 10 g L−1 of dithranol, and 1 g L−1 of sodium trifluoroacetate were mixed at the ratio of 1:1:1, and 1 mL aliquot of this mixture was deposited onto a sample target plate. Gel permeation chromatography (GPC) was measured on a JASCO

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• of 10% of catalyst loading. Interestingly, the protocol employed gem-diols as equivalents of fluorinated aryl/alkyl methyl ketone enolates for the C–C bond formation accompanied the release of trifluoroacetate. This method showed a broad substrate scope including gem-diols with phenyl rings

• -diols was deprived by the amino group of the catalyst, and then the anion attacked isatin from the Re face, followed by release of one mol equivalent trifluoroacetate. The enol anion retrieved the proton from the catalyst to give the (S)-products. In 2013, Chimni and co-workers designed the cinchona

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• to the labile hydrolysis of the trifluoroacetate group. Next, the scope of O-benzoylhydroxylamines was examined with carboxylic acid 1a and olefin 2a (Scheme 3). In the reactions with cyclic O-benzoylhydroxylamines, 5a–c were readily formed in good yields, while acyclic amine products 5d and 5e were

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• fluoroalkylated aromatics. Keywords: β-carbon elimination; carbon–carbon bond cleavage; decarboxylation; tetrahedral intermediate; trifluoroacetate; fluoral; trifluoromethylation; Introduction Organofluorine compounds attract attention because of their applicability in various fields, such as medicine

• perfluoroalkylacetates Trifluoroacetate salts are one of the most readily available trifluoromethylating agents compared to ozone-depleting CF3Br, and expensive CF3I. Sodium trifluoroacetate (CF3CO2Na) is a stable compound at room temperature. Under heating conditions (150–200 °C), CF3CO2Na plays the role of the CF3

• synthesis of 2,2-difluorostyrenes through Mg(0)-promoted defluorinative silylation followed by fluorine-ion-catalyzed 1,2-desilylative defluorination. Buchwald et al. demonstrated aromatic trifluoromethylation using potassium trifluoroacetate (CF3CO2K), CuI and pyridine under flow conditions. Increasing the

Total synthesis of panicein A₂

• Lili Yeung,
• Lisa I. Pilkington,
• Melissa M. Cadelis,
• Brent R. Copp and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 1991–1996, doi:10.3762/bjoc.11.215

• al. demonstrated an efficient, one-step method to synthesise propargyl ethers bearing electron withdrawing groups under mild conditions, achieved through the in situ formation of a trifluoroacetate intermediate and subsequent addition of a phenol [12], a method that has since been utilised in a

• number of syntheses [13][14][15][16][17]. The conversion of alcohol 9 to trifluoroacetate 17 by the addition of trifluoroacetic anhydride and DBU was monitored by TLC and observed to be complete after 1 hour. The phenoxide of phenol 16, prepared by the deprotonation of 16 by DBU, was then added to

• intermediate 17. Unfortunately, the desired product 8 was only obtained in trace amounts. Carbonate intermediates have been shown to be an effective alternative to trifluoroacetate intermediates [18], and have the added advantage to being stable to an aqueous work-up and thus can be isolated. With that

Sequence-specific RNA cleavage by PNA conjugates of the metal-free artificial ribonuclease tris(2-aminobenzimidazole)

• Friederike Danneberg,
• Alice Ghidini,
• Plamena Dogandzhiyski,
• Elisabeth Kalden,
• Roger Strömberg and
• Michael W. Göbel

Beilstein J. Org. Chem. 2015, 11, 493–498, doi:10.3762/bjoc.11.55

• , DIC and HOBt were used as reagents. Coupling of the cleaver proceeded in high yields with no unconjugated PNA detectable in the MALDI mass spectra of the crude products. All conjugates were purified by RP-HPLC and isolated as trifluoroacetate salts. Starting from 20–30 mg of Rink amide MBHA resin

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• centre. Although it is possible to locate assertions in the literature to the possibility of isolating the trifluoroacetate salts after O-acylations with acyl chlorides in CF3CO2H, as reported for L-tyrosine with pivaloyl chloride (the identity of the salt was, however, not determined) [38], it is rather

A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids

• Johanna Trenner and
• Evgeny V. Prusov

Beilstein J. Org. Chem. 2015, 11, 323–327, doi:10.3762/bjoc.11.37

• amounts of Pd trifluoroacetate/dppp [18] gave no conversion. In summary, we have developed a simple and efficient method for the synthesis of 5-hydroxy-3-acyltetramic acids by oxidation of the corresponding bisenolates with molecular oxygen. We have also investigated the cleavage of various protecting

Synthesis of dinucleoside acylphosphonites by phosphonodiamidite chemistry and investigation of phosphorus epimerization

• William H. Hersh

Beilstein J. Org. Chem. 2015, 11, 184–191, doi:10.3762/bjoc.11.19

• triflate as the activator to give the monoamidites 3′-O-(P(N(iPr)2)C(O)R)-5′-O-DMTr-thymidine, and further coupling with 3′-O-(tert-butyldimethylsilyl)thymidine was carried out with activation by pyridinium trifluoroacetate/N-methylimidazole. The new dinucleoside acylphosphonites could be further oxidized

• both 10 and 11 in the 1H and 13C NMR spectra. Since this was not relevant to phosphorus epimerization, it was not further investigated. Dinucleoside coupling was carried out using the 2:1 pyridinium trifluoroacetate/N-methylimidazole (PTFA/NMI) activator developed at Isis to combine phosphonamidites 10

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• trans-(2-trifluoromethyl)cyclopropanecarboxylic acid 23 by way of the Claisen condensation product of ethyl trifluoroacetate (17) with diethyl succinate (18) [25] was used. The conditions for two of the known further steps [26][27] (Scheme 2) had to be modified to achieve acceptable yields. The

Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• 500. MALDI–TOF spectra were performed on a Bruker Ultraflex TOF mass spectrometer, the molecular masses being recorded in linear mode. Dithranol was used as a matrix and sodium trifluoroacetate (NaTFA) as ionization reagent. The samples were dissolved in DMF. DSC measurements were performed using a

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• signals at 1.8 and 4.0 min. The quantum efficiency was determined as described above and displayed in Scheme 5 (Φdis= 0.031). Photolysis of 4-[2-(6-hydroxy-2-naphthyl)-2-oxoethoxy]-4-oxobutan-1-aminium trifluoroacetate (2,6-HNA GABA) Photoproduct analysis. A Pyrex tube was charged with 2,6-HNA GABA (19.5

Syntheses of ¹⁵N-labeled pre-queuosine nucleobase derivatives

• Jasmin Levic and
• Ronald Micura

Beilstein J. Org. Chem. 2014, 10, 1914–1918, doi:10.3762/bjoc.10.199

• = 88.96 Hz, 2H, 15NH2-C2), 6.36 (s, 1H, H-C8), 7.85–7.87 (m, 4H, arom H), 10.42 (d, J = 89.21 Hz, 1H, 15N1-H), 10.81 (s, 1H, NH) ppm. Trifluoroacetate salt of [15N1,15N3,H215N(C2)]-7-(aminomethyl)-7-deazaguanine (1). Compound 8 (70 mg, 0.22 mmol) was added to a solution containing hydrazine hydrate (111

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

•  9). Ionic liquids solubilised included 1,1,3,3-tetramethylguanidinium acetate (TMGA, compound 46, Figure 9), 1,1,3,3-tetramethylguanidinium lactate (TMGL, compound 47, Figure 9) and 1,1,3,3-tetramethylguanidinium trifluoroacetate (TMGT, compound 48, Figure 9). Additives such as methyl orange, CoCl2

An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

• Carla I. Nieto,
• Pilar Cabildo,
• M. Ángeles García,
• Rosa M. Claramunt,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168

• width, 75 kHz; recycle delay, 10 s; pulse width, 2.5 μs and proton decoupling field strength of 100 kHz by SPINAL-64 sequence; recycle delay, 10 s; acquisition time, 25 ms; 128 scans; and spin rate, 25 kHz. The 19F spectra was referenced to ammonium trifluoroacetate sample and then the chemical shifts